["Journal of Traumatic Stress, EarlyView. ", "\nAbstract\nThis study examined the effect of early‐life maltreatment on adolescent psychopathology and whether the significance and magnitude of this effect varied based on the presence of contamination (i.e., when individuals in a comparison group are exposed to maltreatment). Data were drawn from the Longitudinal Studies of Child Abuse and Neglect (LONGSCAN; N = 1,354), a prospective cohort of children at risk for maltreatment. Children in the study were recruited by the time they were 4 years old (Mage = 4.56 years, SD = 0.70), and the sample was 50.8% female and 51.8% Black (25.7% White, 8.0% Hispanic, 1.0% Native American, 0.5% Asian, 11.3% mixed race, 1.7% other). Confirmed indicators characterized maltreatment prior to and after age 4 years. Adolescent self‐report indicators identified maltreatment prior to 16 years of age and corrected contamination. Psychopathology was assessed via self‐report at the LONGSCAN Age 16 assessment. Propensity score analyses indicated that maltreatment prior to 4 years of age only predicted significantly greater adolescent psychopathology symptoms after correcting contamination, B = 6.40, 95% CI [2.02, 10.79], SMD = 0.32, p = .004. Further, effect magnitudes increased 67% by correcting contamination. The results were robust to adjustments for maltreatment reexposure and covariate quality informing propensity score analyses. Correcting contamination can aid the discovery and replication of the effects of early life maltreatment on psychopathology.\n"]